1. Field of the Invention
This invention relates to a folding chair, more particularly to a folding chair including a seat frame and a backrest frame which are provided with interlocking means for locking them against relative movement when the chair is unfolded for use.
2. Brief Description of the Relevant Art
Foldable chairs are designed to be stretchable to a position for sitting by the user and foldable for ease of storage and transport. In order to prevent such a chair from being undesirably folded when in use, locking means is provided therein to lock and stabilize the chair in an unfolded position. An example of a folding chair is shown in FIGS. 1 and 2, wherein a seat frame 11 has two rear end portions which are respectively pivoted to two rear leg members 13 of a U-shaped rear leg frame via pivot shafts 112. The forwardly bending parts 131 of the rear leg members 13 are pivoted to a backrest frame 14. A front leg frame 15 is pivoted to two sides of the seat frame 11 via pivot shafts 113 which also serve to connect pivotally a pair of connecting rods 16 to the front leg frame 15. The front leg frame 15 is further connected to a pair of armrest members 17 at the top ends of the front leg frame 15. A fabric sheet 18 is mounted to the backrest frame 14 and the seat frame 11. When folding the chair 1 by turning the seat frame 11 relative to the rear leg members 13, the seat frame 11 is moved towards the backrest frame 14, and the front and rear leg frames are then turned to the bottom side of the seat frame 11.
In order to prevent the chair from being unfolded when in use, side tubes 111 of the seat frame 11 are provided with protrusions 114 releaseably engage locking plates 19 (only one is shown in FIG. 2) which are turnable about pivot shaft 132 toward the side tubes 111 so as to engage the protrusions 114 with their notches 191. By turning upward the locking plates 19 from the protrusions 114, the seat frame 11 can be folded over the backrest frame 14. Although the locking plates 19 can provide a safe locking effect, they are inconvenient in that they need to be operated by hand for folding and unfolding the chair. In case the user forgets to manipulate the locking plates 19, the chair may undesirably move to its folded position and harm the user.